Built up during the rubber boom of the early 20th century, this jungle-bound city is accessible only by air or boat. As Peru’s busiest freshwater port, punctuated by an expansive canal network lined with floating homes and markets, Iquitos is a departure point for Amazon cruises to Manaus, Brazil. Hop on a boat and cruise past thatched huts, playful parrots and macaws, and jungle scenery.